1-Bromopentane → 1-t-butoxycarbonyl-4-(1-pentyl-1H-benzimidazol-2-yl)[1,4]diazepane

Participants

Reaction Conditions

Reaction Steps

Combine 1-t-butoxycarbonyl-4-(1H-benzimidazol-2-yl)[1,4]diazepane (0.8 g, 2.5 mmol) in dimethylformamide (10 mL). Add sodium hydride (0.13 g, 60% in oil, 3.25 mmol) portionwise. After about 30 minutes, when the gas evolution ceases, add pentyl bromide (0.34 mL, 2.74 mmol). Heat to 80° C. After 18 hours, cool the reaction mixture and dilute with dichloromethane (150 mL) and extract with brine. Dry the organic layer over MgSO4, filter, and evaporate in vacuo to give 1-t-butoxycarbonyl-4-(1-pentyl-1H-benzimidazol-2-yl)[1,4]diazepane: Rf =0.87 (silica gel, 5% methanol/dichloromethane/0.05% concentrated aqueous ammonia). Combine 1-t-butoxycarbonyl-4-(1-pentyl-1H-benzimidazol-2-yl)[1,4]diazepane (0.7 g, 1.8 mmol) and ethanol (5 mL). Add aqueous hydriodic acid (5 mL, 57%). Heat to reflux. After 1 hour, cool to ambient temperature and dilute with diethyl ether (250 mL) and stir to give a solid. Collect the solid by filtration, rinse with diethyl ether, and dry to give the title compound.

Provenance & Evidence